I need some quick info on trains in Italy from a seasoned Italy
traveler.

First, we are considering buying an Italy Rail Pass. It would give
us unlimited travel via rail in first class for four days out of any
month. We would use it to go from Milan to Venice, Venice to
Florence, Florence to Rome and Rome to Naples/Pompei. I have
priced the trips separately and it would save us money to do this.
Any opinions?

Next, with a Rail Pass do I still need to make reservations for
specific trains and times or can we just walk on any train? We
were told that if we want to request a non-smoking, first class
compartment we needed to do that in advance. If we have a Rail
Pass do you have any idea how we would go about that?

We are flying into Milan from Seattle and heading immediately to
Venice. How much time do you think we should allot between
getting off the plane and getting on a train from the airport.

When we leave Florence we are going to take a train to the
airport in Rome in order to take a plane to Palermo. How much
time should we allot ourselves between the two? We would fly
direct from Pisa to Palermo but you have to go through Rome or
Milan and the cost is substantially higher so we thought we
would take a train from Florence to the airport in Rome and fly
from there.

I know these are a lot of questions but you folks are the best and
if you don't have the answers no one will.